左卡尼汀大鼠体内肠吸收动力学的研究

目的考察左卡尼汀在大鼠各肠段的吸收动力学特征。方法应用大鼠在体肠回流试验装置,应用UV法和HPLC法,分别测定肠循环液中酚红和左卡尼汀的量。结果左卡尼汀在药物浓度为0.5、1、2 mg/mL时,全小肠段的吸收速率常数分别为0.187 4、0.179 8、0.174 2/h;不同pH值(7.9、6.5、4.8)时的吸收速率常数分别为0.179 8、0.325 9、0.484 9/h;在十二指肠、空肠、回肠的吸收速率常数分别为0.180 5、0.209 8、0.209 7/h。结论不同的药物浓度、不同肠段对药物在肠道的吸收无显著影响;随着pH值的减小,左卡尼汀的Ka值显著增大;药物的吸收呈一级动力学过程,吸收机制为被动扩散。

Studies on the intestinal absorption kinetics of L-carnitine in rats

Objective To investigate the intestinal absorption kinetics of L-carnitine at rats′ different intestine segments.Methods The rats′ intestine was cannulated for in situ,and recirculation.UV and HPLC were used to determine the concentrations of phenol red and L-carnitine,respectively.Results The absorption rate constant(Ka)at the concentration of 0.5,1,2 mg/mL from intestine were 0.187 4,0.179 8,0.174 2/h respectively.Ka at pH of 7.9,6.5,4.8 from intestine were 0.179 8,0.325 9,0.484 9 /h.Ka at duodenum jejunum and ileum were 0.180 5,0.209 8,0.209 7 /h,respectively.Conclusion Concentration had no effect on the absorption kinetics.In the range of pH 4.8～7.9,the absorption of the drug decrease with the increasing of pH value of the drug solution.L-carnitine can be better absorbed at duodenum jejunum and ileum.The absorption of L-carnitine is a first-order process with the passive diffusion.